As for materials for use in an electric or electronic field, as the speed of transmission signal increases, a low dielectric constant which decreases a time delay and a low dielectric loss tangent which decreases a loss are desired for utilizing a high-frequency wave (gigahertz band). Further, higher toughness is also desired in order to inhibit the occurrence of microcracks thought to be generated by thermal shock and secure high reliability.
For the above demands, the use of engineering plastic such as polyphenylene ether (PPE) is proposed. PPE has excellent high frequency properties. On the other hand, known problems of PPE are that it is poor in compatibility with a thermosetting resin such as an epoxy resin or a cyanate resin, that it has a high melt viscosity so that molding processability is poor, and that a solvent in which it is soluble is limited to an aromatic hydrocarbons solvent such as toluene, benzene or xylene and an halogenated hydrocarbon solvent such as methylene chloride or chloroform so that workability is poor.
For improving compatibility, a method of improving compatibility by blending PPE with a different resin as a compatibilizing agent is discussed and the pseudo IPN structuralization of a cyanate resin is also discussed (JP-A-11-21452, etc.). However, the problems of molding processability and heat resistance have not been solved yet. Further, a method of converting a high molecular PPE into a low molecular compound is discussed for improving moldability. For example, there are known a method in which a high molecular PPE and a bivalent phenol are redistributed in the presence of a radical catalyst (JP-A-9-291148, etc.) and a method in which a bivalent phenol and a monovalent phenol are subjected to oxidation polymerization (JP-B-8-011747). In each of the above methods, a high molecular substance is presence so that it is impossible to obtain a bifunctional low molecular oligomer effectively.
Further, an epoxy acrylate compound has been widely used as raw materials for various functional high molecular materials such as a photosensitive material, an optical material, a dental material, an electronic material and crosslinking agents for various polymers. However, since higher performances are being required in these application fields in recent years, physical properties required as a functional high molecular material become severer increasingly. As such physical properties, for example, heat resistance, weather resistance, low water absorptivity, high refractive index, high fracture toughness, low dielectric constant and low dielectric loss tangent are required. Until now, these required physical properties have not been necessarily satisfied. For example, concerning the production of a printed wiring board, it is known that an epoxy acrylate compound is used for a photo solder resist used as a permanent mask. As a resist material like above, there are known a novolak type epoxy acrylate compound disclosed in JP-A-61-243869, a bisphenol fluorene type epoxy acrylate compound disclosed in JP-A-3-205417 and acid-modified products of these epoxy acrylate compounds. In a use for a printed wiring board, heat resistance in an immersion in a solder bath is demanded. When the heat resistance is insufficient, swelling or peeling off of a resist film occurs, which causes defectives. In compliance with an increase in the speed of transmission signal, recently, in addition to the above-mentioned heat resistance, a lower dielectric constant which decreases a time delay and a lower dielectric loss tangent which decreases a loss are desired for utilizing a high-frequency wave (gigahertz band). However, a conventional epoxy acrylate compound is insufficient in dielectric characteristic corresponding to a high-frequency wave. For this reason, a novel epoxy acrylate compound which satisfies the above requirements is demanded.
On the other hand, as a thermosetting resin, there are known a polyphenylene ether modified epoxy resin, a thermosetting type polyphenylene ether and the like. A conventional thermosetting resin has problems with regard to workability, moldability, heat resistance or the like. That is, problems are that, when a varnish is prepared by using the conventional thermosetting resin, a solvent is limited, and that due to a high melt viscosity, a high multilayer formation can not be carried out and a high temperature and a high pressure are required at a molding time. Further, a cyanate ester resin is known as a thermosetting resin having excellent dielectric characteristic and excellent moldability. However, when a cyanate ester resin alone is used, a cured product is too hard and is fragile so that it has a problem with regard to adhesive property and solder resistance. When a cyanate ester resin is used in combination with an epoxy resin, the above defects can be covered to some extent. However, it is difficult to cope with requirements of lower dielectric characteristics for laminates, which requirements are becoming severer, by using a conventional cyanate ester resin in combination with a conventional epoxy resin. Further, the coexistence of lower dielectric characteristics and flexibility is difficult.
Concerning a semiconductor device, an epoxy resin composition is generally used for sealing electronic parts such as a semiconductor. The above-mentioned epoxy resin composition is composed of various epoxy resins such as a cresol novolak type epoxy resin, a bisphenol A type epoxy resin and a biphenyl type epoxy resin, a curing agent therefor, an inorganic filler, a curing accelerator as required, a coupling agent, a releasing agent, a coloring agent and the like.
In compliance with recent requirements for a decrease in size or a decrease in thickness, the formation technique of the above electronic parts is being changed from a conventional through hole mounting method (DIP: dual inline package, etc.) to a surface mounting method (SOP: small outline package, QFP: quad flat package, etc.). In the surface mounting method, since a semiconductor device is treated at a high temperature (for example 210° C.˜260° C.) at a solder reflow or the like at a mounting time, a high temperature heat is applied to the entire semiconductor device. In this case, problems such as the occurrence of cracks in a sealing layer formed of the above epoxy resin composition and a large decrease in humidity resistance are apt to occur. For example, when a thin sealing layer having a thickness of 2.0 mm or less is used, cracks are apt to occur at the time of a solder reflow. In view of a further improvement in physical properties and an increase in a signal transmission speed in a chip circuit, it is demanded to carry out a sealing with a sealing layer having a lower dielectric constant.
Countermeasures against the above are proposed. One countermeasure with respect to handling is that a semiconductor device before mounting is packaged in a moisture-proof case. As an improvement in a sealing epoxy resin composition, for example, JP-A-1-108256 discloses a sealing material containing a biphenyl type epoxy resin and JP-A-64-24825 discloses a sealing material containing an epoxy resin and a polyphenylene ether type resin in combination.
Further, a (meth)acrylate compound have been widely used as raw materials for various functional high molecular materials such as a photosensitive material, an optical material, a dental material, an electronic material and crosslinking agents for various polymers. However, since higher performances are being required in these application fields in recent years, physical properties required as a functional high molecular material become severer increasingly. As such physical properties, for example, heat resistance, weather resistance, low absorptivity, high refractive index, high fracture toughness, low dielectric constant and low dielectric loss tangent are required. Until now, these required physical properties have not been necessarily satisfied.